Messier 41

Messier 41

Messier 41 (M41) is a bright open star cluster located in Canis Major constellation. It lies near Sirius, the brightest star in the sky. Messier 41 occupies an area of 38 arc minutes in apparent diameter, roughly the size of the full Moon, with an estimated age between 190 and 240 million years. The cluster is detached from the surrounding star field with strong concentration at the center.

Visible From Pacific NorthwestDecember to February
Best Time To ObserveJanuary
Minimum Size Of Viewing DeviceSmall Telescope
Object TypeOpen Cluster
DesignationsMessier 41, M41, NGC 2287, Collinder 118, C 0644-206, OCl 597.0, MWSC 0978 
Right Ascension06h 46.0m
ConstellationCanis Majoris
Number Of Stars100
Apparent magnitude +4.5
Apparent dimensions 38′
Object Radius12.5 light years
Distance From Earth2,300 light years


Messier 41 was discovered by the Italian astronomer Giovanni Battista Hodierna before 1654 and possibly seen by Greek philosopher and scientist Aristotle around 325 BC. It is uncertain whether the philosopher saw the cluster, a comet, or part of the Milky Way near the star d Canis Majoris.

English astronomer John Flamsteed discovered the open cluster independently on February 16, 1702, as did the French astronomer Guillaume Le Gentil in 1749.

Charles Messier added the cluster to his catalogue on January 16, 1765, describing it as a “cluster of stars below Sirius, near Rho Canis Majoris,” adding that “this cluster appears nebulous in an ordinary telescope of one foot [FL]; it is nothing more than a cluster of small stars.”

Locating M41 In The Sky

M41 is very easy to find as it lies about 4 degrees south of Sirius, the Dog Star, one of the nearest stars to Earth. M41 can be seen in the same binocular field with Sirius and Nu-2 Canis Majoris, an evolved orange giant with a visual magnitude of 3.95. The cluster forms a triangle with the two stars. In clear, dark skies, it is visible to the naked eye.

Messier 41

Viewing M41

The cluster is relatively loose and can be resolved in a small telescope. It is best observed at low magnifications. 10×50 binoculars show a large faint patch of light, while larger binoculars resolve some of the stars in the cluster. Small telescopes, 4-inch, resolve about 50 stars, while 6-inch and 8-inch telescopes show many more fainter members. The best time of year to observe M41 is in the months of December, January and February.

Photographing M41

In the winter, Messier 41 can indeed be a target that one can indeed hit with just a DSLR, auto guiding, and a larger telescope. Being an open cluster, autoguiding is crucial to be on point to prevent the stars from trailing. Accurate guiding will assist with star crispness. Filters will help bring out the color, and it should not take too much time to obtain a good image of M41.

Sources And Further Reading

Descriptions of all of Messier Objects can be found here.

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